Batteries not being charged while towing

[Will & Cindy]

Everything works. But the batteries are not being charged while driving/towing. All is ok when plugged into shore power.

 

[Carl n Susan]

Truck 12V power to the RV is carried on pin #4 of the Bargman plug. Even if everything is working, the best it can deliver is around 5 amps. Not a lot and definitely not enough to charge a battery.

Check that the fuse for the Charge Line is installed in the truck and 12V power is discernible at the connector at the back of the truck. There are reported cases of the fuse not being installed or it being blown.

Assuming the truck is providing 12V on the Charge Line, next check for 12V at the battery after plugging in the RV to the truck. The circuit flow from the truck is through the umbilical cord to the 4" sq. box on the pin, then down to the battery. Look along this route for a break in the wiring or connections.

Be aware the truck 12V Charge Line is not capable of keeping a battery charged if you have a residential refrigerator.

 

[Daryles]

Check your trucks owners manual for the location of the 12vdc charging fuse AND RELAY.
I have read of people discovering the fuse and relay were missing from the factory.

 

[Will & Cindy]

Check your trucks owners manual for the location of the 12vdc charging fuse AND RELAY.
I have read of people discovering the fuse and relay were missing from the factory.

I’ve located the 30 amp fuse. Trying to figure out how to get it out to check it. Only 2 or 3 inches of space around it.
Thanks for the reply.

 

[scottz]

You didn't say what kind or quantity batteries you have. You might get a little from the OEM 12V feed, but it's like using a straw when you need a fire hose.

 

[Daryles]

I installed a DC-DC charger.

DC to DC charger

I just finished installing a Renogy 60A DC-DC charger in my 5th wheel. The purpose of this is to be able to charge your RV batteries from your truck "safely" whether parked or driving. The 7 way cable from the truck to the RV does provide some charging. The most I have measured is about 7A. It...

www.montanaowners.com

 

[RMcNeal]

That's on my list, too. It should have already been done since I have a residential fridge.

 

[Will & Cindy]

Truck 12V power to the RV is carried on pin #4 of the Bargman plug. Even if everything is working, the best it can deliver is around 5 amps. Not a lot and definitely not enough to charge a battery.

Check that the fuse for the Charge Line is installed in the truck and 12V power is discernible at the connector at the back of the truck. There are reported cases of the fuse not being installed or it being blown.

Assuming the truck is providing 12V on the Charge Line, next check for 12V at the battery after plugging in the RV to the truck. The circuit flow from the truck is through the umbilical cord to the 4" sq. box on the pin, then down to the battery. Look along this route for a break in the wiring or connections.

Be aware the truck 12V Charge Line is not capable of keeping a battery charged if you have a residential refrigerator.

Ford has a crazy setup for the 12v live feed to the camper. It has more than one trigger that activates the live feed. I read that the truck has to be running , doors locked , in gear and engine at 2000 rpm’s just to check the voltage.
I have new batteries in the truck and the Montana.

 

[mdpcjjjj]

I had to change out this relay thing to fix the issue.

 

[Oregon Coast]

Simply put, a vehicle charging system is designed to keep the onboard battery charged. Per se, an 80 amp alternator will only put out a lot of amps when the load on the (truck) battery is high, or is in a discharged state. Notice the large wire sizes going to the battery, alternator, and starter, quite large for higher amps. The battery/charging wire going to the towed vehicle is small in comparison. If you could trick the tow vehicle charging system to put out high amps and route these amps, to the towed vehicle, you would melt that small battery/charging wire quickly. I have never heard or read of an easy fix. Except (but not easy) to add an additional alternator, related controls and wiring to the vehicle engine and wire to the house batteries, this was done on an MCI Bus Conversion and worked great.